A research team led by Dr Tim Sutton of the Australian Centre for Plant Functional Genomics at the University of Adelaides School of Agriculture, Food and Wine at the Waite Campus made the discovery.

The gene, known as Bot1, was first identified in a boron-tolerant African barley known as Sahara.

Bot1 helps barley plants survive in soils containing high amounts of boron, common to much of Southern Australia, Asia and Africa. The gene works by preventing the access and accumulation of boron in the plant, which causes the damage and limits growth.

Highly boron-tolerant barley landraces (crop varieties) had been previously identified, but nothing was known about the molecular basis of their tolerance, says Dr Sutton.

We used genomics, which is a combination of modern molecular biology techniques, to identify the sequence of the boron-tolerant gene from Sahara, and the underlying molecular mechanism that provides the tolerance, he added.

Professor Peter Langridge, CEO of the Australian Centre for Plant Functional Genomics said: Boron is an essential micronutrient for plants but they require just the right amount, and boron toxicity and deficiency severely limit crop production worldwide.

This discovery means that farmers growing barley in high boron environments will be able to choose varieties of barley more suited to their soils, therefore minimising crop loss to this condition, he added.

Researchers say that scientists can now work towards transferring this gene into commercially vital barley varieties using either conventional breeding or transformation techniques.

Boron toxicity appears in the tips of the older leaves first, turning them yellow with characteristic brown spots. It then extends down the leaf as toxicity increases until it causes tissue death and eventually plant death.

Thirty per cent of South Australias grain growing soils are affected by high levels of boron.